I remember back in the day playing Sierra's the Realm where trading consisted much like it does here by dropping an item on the ground and hopefully the other player drops the payment for you in return..
There are better ways to do it just as what existed in World Of Warcraft that leaves little room for scammers.
Someone wants to buy your rabbit skin, you right click the player and open a trade menu, then place the rabbit skin inside the trade window where the buying player can inspect it. The buying player can then place payment in his trade window, both players can now see all items taking place in the transaction. Both players click confirm and the items are traded.. simple and safe..